Eye‐Targeted <scp>A20</scp> Gene Therapy Alleviates Ischemic Retinopathy by Reducing Pathologic Neovascularization, Gliosis, and Neuronal Apoptosis

Intravitreal administration of anti-VEGF therapies has been highly beneficial in treating ischemic proliferative retinopathies (PR). However, a quarter of patients do not benefit from these therapies due to primary or secondary non-response and adverse side effects. The limited success of anti-VEGF therapies underscores the complex interplay between the various pathogenic contributors to this disease. Mechanistic studies have emphasized the importance of pathologic angiogenesis, reactive inflammatory gliosis, and heightened neuronal apoptosis as key determinants of disease outcomes. We surmise that therapeutic strategies targeting all three components would be highly valuable. Through gain and loss-of-function studies of A20/TNFAIP3, a ubiquitous NF-κB inhibitor with established cytoprotective functions in endothelial and neuronal cells, we uncovered a novel function for this gene as a physiologic regulator of angiogenesis in human retinal endothelial cell cultures. In vivo, intravitreal delivery of an A20 gene therapy, which yields transgene expression throughout retinal layers, significantly reduces central vaso-obliteration and pathological peripheral neovascular tuft formation in a mouse model of oxygen-induced PR. In contrast, mice with total or partial A20 knockdown exhibited worse lesions. Remarkably, A20-related benefits were associated with a significant reduction in inflammatory gliosis and improved glial function, notably in Müller cells, as evaluated by glial fibrillary acid protein (GFAP) and glutamine synthetase (GS) immunostaining, and with decreased apoptotic cell death across the retina, including in neuronal cells. Conversely, A20 knockdown aggravated these features. By concurrently reducing pathologic neovascularization, reactive gliosis, and neuronal apoptosis in the retina, A20 emerges as a unique therapeutic target with promising translational potential.